/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// Adapted from Apache Arrow.

#pragma once

#include "arrow/util/bit_util.h"
#include "arrow/util/endian.h"
#include "velox/dwio/parquet/writer/arrow/LevelComparison.h"

// Used to make sure ODR rule isn't violated.
#ifndef PARQUET_IMPL_NAMESPACE
#error "PARQUET_IMPL_NAMESPACE must be defined"
#endif

namespace facebook::velox::parquet::arrow::internal {
namespace PARQUET_IMPL_NAMESPACE {

/// Builds a bitmap by applying predicate to the level vector provided.
///
/// \param[in] levels Rep or def level array.
/// \param[in] num_levels The number of levels to process (must be [0, 64])
/// \param[in] predicate The predicate to apply (must have the signature `bool
/// predicate(int16_t)`.
/// \returns The bitmap using least significant "bit" ordering.
///
template <typename Predicate>
inline uint64_t
LevelsToBitmap(const int16_t* levels, int64_t num_levels, Predicate predicate) {
  // Both clang and GCC can vectorize this automatically with SSE4/AVX2.
  uint64_t mask = 0;
  for (int x = 0; x < num_levels; x++) {
    mask |= static_cast<uint64_t>(predicate(levels[x]) ? 1 : 0) << x;
  }
  return ::arrow::bit_util::ToLittleEndian(mask);
}

inline MinMax FindMinMaxImpl(const int16_t* levels, int64_t num_levels) {
  MinMax out{
      std::numeric_limits<int16_t>::max(), std::numeric_limits<int16_t>::min()};
  for (int x = 0; x < num_levels; x++) {
    out.min = std::min(levels[x], out.min);
    out.max = std::max(levels[x], out.max);
  }
  return out;
}

inline uint64_t
GreaterThanBitmapImpl(const int16_t* levels, int64_t num_levels, int16_t rhs) {
  return LevelsToBitmap(
      levels, num_levels, [rhs](int16_t value) { return value > rhs; });
}

} // namespace PARQUET_IMPL_NAMESPACE
} // namespace facebook::velox::parquet::arrow::internal
